Copiers and printers containing photoconductors create a latent image which is developed by using toner. The toner on the photoconductor then transfers to paper or appropriate intermediate which then travels through a heater which fixes the toner particles on the paper. The transfer of toner particles from the photoconductor to the paper or intermediate is not 100% complete. There are residual toner particles on the photoconductor that need to be removed. It is common to remove the remaining toner particles on the photoconductor after each transfer process by using a cleaning device, such as a cleaning blade.
Non-magnetic single component development (SCD) toner requires high flowability and high chargeability because the time for toner to flow through the contacting nip formed between the charge blade and the development roll is very short. Low charge causes reduced solid area development, increased toner dusting in white areas of the page (background), poor development stability over time, ghosting, and/or white bands.
For good cleaning performance of any un-transferred toner, the forces acting near the cleaning blade are such that there is sufficient force against the photoreceptor to prevent toner from getting underneath, but not so much force to damage the cleaning blade edge during operation and continued print cycles. Cleaning performance degrades when the edge of the blade wears, the photoreceptor surface becomes damaged, or the urethane properties become unstable over time. Cleaning performance may also degrade when the toner particles are spherical and thereby tend to roll under the cleaning blade nip.
Cleaning performance may be improved by adding acicular surface additives, for example, acicular titanium dioxide, during the blending of the toner particles. The acicular surface additive is not blended into the toner particles, but rather mixed in and loosely dispersed among the toner particles.
In addition, cleaning performance may be improved by lubricating the cleaning blade with various lubricating powders, for example, zinc stearate and graphite fluoride, to reduce surface forces on the cleaning blade. Lubrication can be achieved by dusting the cleaning blade with powders or coating the cleaning blade with a solution including the lubricating powders. Unfortunately, these lubricant powders do not remain adhered to the cleaning blade and create frictional forces that damage the blade edge, which inherently causes toner to get under the blade and create image defects.
There remains a need for a cleaning blade and lubricant for an electrophotographic printing device that minimizes toner particles from rolling underneath the cleaning blade, particularly spherical shaped toner particles.